It can be hard to tell if there are bats about, since they only come out at night. But, no more. With the flip of a switch our new Bats in the Belfry Bat Detector will home in on any passing bat's ultrasonic squeaks, translating the sound into a frequency you can hear. Detector also comes with headphone jack and a LED that gives you a visual signal. Free downloadable sound analytic software is also available. Headphones and battery not included: Our Bat Detector will tell you low and clear. As bats fly and hunt they send out ultrasonic sound waves, a kind of radar they use to avoid objects and pick out prey. These ultrasonic sound waves are at a pitch too high for us humans to hear. But, not too high for our Bat Detector. Its sensitive ultrasonic transducer picks up ultrasonic waves in the 25-100 Khz range, translates them into sound we can hear and broadcasts that sound through the Bat Detector's loud speaker. There's even a bright red LED that goes off to give you a visual cue. Also comes with a headphone jack so you can listen more privately. Can be plugged into a recorder and bat feeding frenzies captured on tape. Then download the free sound analytic software, and analyze the calls.